JPH05330028A - Transferring ink jet printer - Google Patents

Abstract

PURPOSE:To obtain a high quality image at a low transfer pressure without producing vapor and being affected on time from printing to transfer and a printing pattern, in an ink jet printer of a transfer type. CONSTITUTION:An ink image is formed on a transfer drum 1 from droplets of ink jetted by an ink jet recording-head 2, and subsequently irradiated with ions by a corotron electrifier 3, thereby fixing color particles constituting the ink image to the surface of the transfer drum 1. The transfer drum 1 on which the ink image is formed is coated with a solvent 20 by a solvent application means 4 and then the thickness of the coating of solvent is regulated by a coating-thickness regulating roller 21 so as to be uniform, so that an concentrated-ink image is formed. The concentrated-ink image on the transfer drum 1 is transferred to a recording sheet 8 by a transfer pressure roller 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly to a transfer type ink jet printer which forms an ink image on a transfer medium and then transfers the ink image onto the recording medium to obtain the ink image on the recording medium. Regarding

[0002]

2. Description of the Related Art As a transfer type ink jet printer, a method disclosed in US Pat. No. 4,538,156 is known.

As shown in FIG. 7, this is a recording head 10.
1, the ink image formed on the surface of the cylindrical transfer medium 100 is applied to the pressure roller 104 from the rear surface of the recording medium 102.
And press to transfer by pressure. The untransferred residual ink is removed by the cleaning device 103.

This conventional transfer type ink jet printer has a problem that the quality of the transferred image is poor. This is because, firstly, when the ink image made of the liquid ink comes into contact with the recording medium, it soaks along the fibers of the recording medium and the peripheral portion of the ink image becomes a whisker. Second
Since the transfer is performed by the contact between the transfer medium and the recording medium, the concave portion does not contact the recording medium and the transfer medium and the image to be transferred is not transferred to the recording medium having low smoothness. It became a so-called "blank" state.

To address such a problem, the applicant of the present invention disclosed in Japanese Patent Laid-Open No. 62-92849 discloses that ink droplets are once ejected onto a transfer medium, where the solvent components in the ink droplets are evaporated and concentrated. A device for pressing and transferring ink onto recording paper has been proposed. This is as shown in FIG.
Ink is ejected onto the transfer medium 202 from 01, and the heater 20
3 accelerates the evaporation of the solvent component of the ink, and the roller 20
4 is pressed and transferred to the recording medium 205 supported by 4. The transfer medium after the transfer is cleaned by the brush 206 and dried by the blower 207 to have a constant surface state. This is a concentrated ink recording medium 2
05, the ink image does not deform during transfer,
Further, it does not soak into the recording medium 205. Therefore, the above-mentioned problems of the transfer type ink jet printer are solved and a clear image can be formed.

[0006]

However, since the heater 203 is used for concentrating the ink image, there is a problem to be solved further. First, there is a problem in that the inside of the apparatus is contaminated because the solvent vapor is discharged into the inside of the apparatus with the evaporation of the solvent.

Secondly, there is a problem that the transfer pressure becomes large. That is, even if the amount of heat of the heater 203 is set to an appropriate value and the concentrated state is specified, when scanning is performed with the one-nozzle head or the multi-nozzle head, the time from ink ejection to transfer differs depending on the place, and the concentrated state There will be a difference. Here, regarding the relationship between the concentration state of the ink image and the transfer pressure, the transfer pressure tends to increase as the ink image concentration increases. Therefore, it is necessary to set the pressure value according to the maximum concentration state of the ink image. There was too much pressure. Further, the ink image printing pattern, in other words, the amount of ink per unit area also causes the ink image concentration state to vary, which requires an excessive transfer pressure.

The present invention solves such a problem, and an object thereof is to obtain a good image at a low transfer pressure without generation of steam, and without being affected by a time from printing to transfer or a print pattern. Another object of the present invention is to provide a transfer type inkjet printer.

[0009]

A transfer type ink jet printer according to the present invention comprises an ink in which colored particles are dispersed in a solvent, an ink jet recording head for ejecting the ink as ink droplets, and carrying the ink droplets. Further, the inkjet recording head includes a transfer medium that moves through a gap and a transfer unit that transfers an ink image from the transfer medium to the recording medium. After forming the ink image on the transfer medium, the transfer medium reaches the transfer unit. In between, an ion irradiation means for irradiating the ink image formed on the transfer medium, a solvent applying means for applying a solvent, and a solvent thickness regulating means for making the thickness of the solvent constant are sequentially provided. Characterize.

[0010]

The details of the present invention will now be described with reference to the illustrated embodiments.

FIG. 1 is a perspective view of a transfer type ink jet printer according to a first embodiment of the present invention. Around the transfer drum 1 which is a transfer medium, an inkjet recording head 2, a corotron charger 3 which is an ion irradiation means, a solvent application means 4, a solvent thickness regulation means 5, a transfer pressing roller 6 which is a transfer means, a transfer drum cleaning device. 7 and 7 are sequentially arranged.

The transfer drum 1 is constructed by providing a conductive elastic layer 11 around a metal tube 10. Conductive elastic layer 11
Can be obtained from a rubber material in which a conductive compound such as carbon black or metal powder is dispersed. Transfer drum 1
Are rotatably supported in the direction of arrow A in the figure with a certain gap with respect to the inkjet recording head 2. The inkjet recording head 2 is an inkjet recording head of a type using a piezoelectric element, and has a plurality of nozzles arranged in the axial direction of the transfer drum 1 at regular intervals.

The corotron charger 3 is an ion generator using a corotron and has a structure in which a tungsten wire 12 having a diameter of 0.05 mm is shielded by a stainless steel housing 13 while keeping a distance of about 7 mm. A high voltage power supply 14 is connected to the tungsten wire 12, and a negative corona ion can be generated by applying a high voltage of -5 kV.

The solvent applying means 4 is composed of a solvent container 15 for containing a petroleum solvent 20 which is a solvent forming ink, a pump 16 and an application head 18 having a slit 17, and the slit 17 is provided on the transfer drum 1. It is arranged to face.

The coating thickness regulating means 5 is provided inside the solvent container 15 and includes a coating thickness regulating roller 21, a peeling plate 22 for removing the solvent adhering to the surface of the coating thickness regulating roller 21, and a coating thickness regulating roller 21. It is composed of race rings 23 attached to both ends.

The transfer pressing roller 6 is a metal roller made of aluminum, and is configured so that pressing or releasing of the transfer drum 1 can be controlled by pressure applying means (not shown). It rotates at the same speed as the peripheral speed of the transfer drum 1 in the direction of arrow B in the figure.

The transfer drum cleaning device 7 comprises a cleaning blade 25 made of urethane rubber and a housing 26. Cleaning blade 25
Is connected to a driving means (not shown), and its edge can be brought into contact with or released from the surface of the transfer drum 1.

In this embodiment, the ink used is one in which colored particles are dispersed in a petroleum solvent. That is, as the petroleum solvent, Isopar L manufactured by Exxon Chemical Co., Ltd. is used, and it has a characteristic that it is difficult to volatilize at room temperature. The colored particles are composed of Raven 1255 manufactured by Columbian Carbon Co., Ltd. as a pigment and ethyl cellulose as a resin, and are negatively charged by being dispersed in Isopar L together with a charge control agent.
This is used by adjusting the solid content concentration to 25 wt%.

Next, the operation will be described. In the initial state in which the recording signal is not input, the transfer pressing roller 6 and the cleaning blade 25 of the transfer drum cleaning device 7 are held in a state in which the contact state or the pressed state with respect to the transfer drum 1 is released. A cross-sectional view taken along the virtual plane H shown in FIG. 1 is shown in FIG. In the drawing, the contacting or pressing state of the transfer pressing roller 6 and the cleaning blade 25 is shown by a solid line, and the released state is shown by a broken line with 6'and 25 ', respectively. In the initial state, they are held at the positions indicated by broken lines.

Next, when a recording signal is input to the ink jet recording head 2 while maintaining this state, an ink image is formed on the outer peripheral surface of the transfer drum 1. An ink image forming operation by the inkjet recording head 2 will be described with reference to FIGS. 1 and 3. FIG. 3 is a view seen from the direction of arrow D in FIG. The inkjet recording head 2 has a configuration in which a plurality of nozzles 30, 31, 32, ... Are aligned with the axial direction of the transfer drum 1 (direction of arrow E in the drawing) and arranged at a pitch of 8 × 1/300 inches. In accordance with the recording signal, the ink is made into ink droplets and the plurality of nozzles 30, 3
, 32 are selectively discharged. The inkjet recording head 2 configured as described above is used for the transfer drum 1 during recording.
In synchronism with the rotation of, the moving means 19 feeds 1/300 inch in the axial direction of the transfer drum 1, 30 ′, 3
Move to the positions indicated by 1 ', 32' ... That is, each time the transfer drum 1 makes one revolution, the inkjet recording head 2
Moves in the axial direction of the transfer drum 1 and is repeated eight times, whereby an ink image can be formed in a predetermined recording area 28 on the transfer drum 1 at a 1/300 inch pitch. Then, the inkjet recording head 2 moves to the initial position. The moving means 19 is composed of a cam 35 and a motor 36. As described above, by configuring the inkjet recording head 2 and performing the ink image forming operation, the pitch of the nozzles of the inkjet recording head 2 may be 8 times the pixel pitch on the transfer drum 1,
The manufacturing can be simplified and the manufacturing cost can be reduced. Further, since the ejection from the inkjet recording head 2 is performed in a low viscosity state, good ejection characteristics can be obtained, and a high quality ink image can be stably obtained on the transfer drum 1.

By performing the above operation, an ink image is recorded over the entire recording area 28. When the ink image forming operation is completed, negative corona ions are irradiated by the corotron charger 3 to separate the ink image into colored particles and a petroleum solvent. The ink separating action of the corotron charger 3 will be described in detail with reference to FIGS. 4 and 5. In this embodiment, the colored particles 41 are negatively charged, and the transfer drum 1 is connected to the ground. In the ink image 40 on the transfer drum 1, colored particles 41 are uniformly dispersed in a petroleum solvent 42, as shown in FIG.
Here, negative corona ions 43 are generated by the corotron charger 3.
Is irradiated, the surface of the ink image 40 is negatively charged as shown in FIG. 5, and the colored particles 41 receive electrostatic force and adhere to the surface of the transfer drum 1. At this time, the droplet shape of the petroleum solvent 42 decreases in the height direction of the ink image 40 in FIG.
Although it is enlarged compared to the contact area between the ink droplet 40 and the transfer drum 1, the colored particles 41 are directed toward the surface direction of the transfer drum 1 while maintaining the contact area between the ink image 40 and the transfer drum 1 in FIG. It moves and becomes a concentrated ink image in the vicinity of the transfer drum 1. That is, the ink image 40 in which the colored particles 41 are dispersed is the corona ion 4
It is possible to separate the concentrated colored particles 41 and the petroleum-based solvent 42 by irradiating with 3. Transfer drum 1
Corona ions 43 are also present in the portion 44 where the ink image 40 is not present.
However, since the transfer drum 1 is electrically conductive, it is not charged. The timing of irradiating the corona ions 43 by the corotron charger 3 may be synchronized with the ink image forming operation. That is, not only is the corona ion 43 uniformly irradiated after the ink image forming operation is completed, but in this embodiment, the corotron charger 3 synchronizes with each rotation of the transfer drum 1 during the ink image forming operation. The corona ions 43 may be irradiated. In particular, due to the wettability between the surface of the transfer drum 1 and the ink,
This is effective when the ink image 40 easily flows or when it is difficult to get wet and the ink droplets collect together. This is because it has the above-described action of fixing the colored particles on the surface of the transfer drum 1 faithfully according to the recording signal.

Next, the petroleum solvent 20 constituting the ink is uniformly applied to the surface of the transfer drum 1 by the solvent applying means 4. This is because the petroleum solvent 20 stored in the solvent container 15 is supplied to the coating head 18 by the pump 16 so that the petroleum solvent 20 is discharged from the slit 17 and is uniformly coated on the surface of the transfer drum 1. To do. Here, when the petroleum solvent 20 is applied from above the ink image, the application pressure acts on the colored particles, but the colored particles 4
Since a mirror image force acts on the surface of No. 1 with the surface of the transfer drum 1, the colored particles 41 are not disturbed. Further, the coating thickness of the petroleum solvent 20 by the solvent coating means 4 is determined by the coating thickness regulating means 5 described later, and in the present embodiment, it is necessary to coat the petroleum solvent 20 thicker than the distance between the coating thickness regulating roller 21 and the transfer drum 1. is there.

The transfer drum 1 to which the petroleum-based solvent is evenly coated is regulated by the coating thickness regulating roller 21 to a predetermined thickness. The coating thickness regulating roller 21 is equipped with race rings 23 at both ends and abuts against the transfer drum 1 to rotate in the direction of arrow C in the figure with a distance of 0.3 mm from the transfer drum 1. As a result, a force due to the fluid viscosity is applied to the petroleum solvent 20 in the minute gap between the transfer drum 1 and the coating thickness regulating roller 21 to peel it off from the surface of the transfer drum 1, and the surface of the transfer drum 1 The petroleum solvent 20 can be regulated to have a predetermined thickness.
Since the above-mentioned mirror image force acts on the colored particles 41 of the ink image, the colored particles 41 are not separated from the surface of the transfer drum 1. In this embodiment, the peripheral speed of the coating thickness regulating roller 21 is set so that the thickness of the petroleum solvent 20 is 5 μm or less, and a concentrated ink image is formed on the transfer drum 1. The petroleum solvent 20 adhering to the surface of the coating thickness regulating roller 21 is removed by the peeling plate 22, and is made to flow down and be held in the solvent container 15.

Next, the transfer drum 1 and the transfer pressing roller 6 are brought into contact with each other, a pressure is applied, the recording paper 8 is passed through this pressing portion, and the ink image on the transfer drum 1 is recorded by the applied pressure. Transfer to 8. At this time, since the ink image is kept in a proper wet state, a high quality image can be obtained on the recording paper 8 with a low pressure.

When the transfer of the ink image to the recording paper 8 is completed, the cleaning blade 25 is brought into contact with the transfer drum 1, and the residual ink image on the transfer drum 1 is separated and removed. After a predetermined time has passed, the cleaning blade 25
Becomes a state in which the original contact state is released.

The ink image on the transfer drum 1 can form a concentrated ink image without using the evaporation means by passing through the coating thickness regulating roller 21. Therefore, it is possible to prevent the inside of the apparatus from being contaminated due to the generation of the vapor of the petroleum solvent that constitutes the ink. Further, since the petroleum solvent is applied uniformly after the ink image forming operation is finished to regulate the thickness to a predetermined thickness, it is possible to form an ink image in a uniform concentrated state. Therefore, a good image can be obtained at a low transfer pressure, which is not affected by the time from printing to transfer or the print pattern.

In this embodiment, the polarities of the corona ions irradiated by the corotron charger are the same as the charging polarities of the colored particles constituting the ink, but the same applies when the corona ions of the opposite polarity are irradiated. The effect of was obtained.

FIG. 6 is a perspective view of a transfer type ink jet printer according to the second embodiment of the present invention. Around the transfer belt 9 which is a transfer medium, an inkjet recording head 2, a corotron charger 3, a solvent coating means 4, a solvent thickness regulating means 5,
Transfer pressing roller 6, transfer belt cleaning pad 50
And are arranged in sequence. The transfer belt 9 is suspended by a transport mechanism including a driving roller 51, a driven roller 52, and a tension roller 53, and is transported in the direction of arrow F in the figure. Tension roller 53, driven roller 5
2. The inkjet recording head 2, at a position facing the drive roller 51 via the transfer belt 9,
Solvent coating means 4, solvent thickness regulating means 5, transfer pressing roller 6
Are arranged respectively. The ink used in this example is
It is composed of the same petroleum solvent and colored particles as in the first embodiment.

The transfer belt 9 is formed by laminating a conductive elastic layer on an endless belt made of a metal such as nickel, and the rubber material shown in the first embodiment can be used as the conductive elastic layer. The solvent coating means 4 and the coating thickness regulating means 5 are partially integrated. The solvent applying means 4 has a structure in which a solvent supply slit 60 is connected via a supply pump 61 to a solvent tank 62 containing a petroleum solvent. In addition, the coating thickness regulating means 5 includes a solvent recovery slit 65.
Is connected to the solvent tank 62 via the recovery pump 66. The solvent supply slit 60 and the solvent recovery slit 65 are integrally formed by a member 67, and the openings of the respective slits are arranged along the axial direction of the driven roller 52.

Next, the operation will be described. Since the ink image forming operation by the ink jet recording head 2 and the corona ion irradiation operation by the corotron charger 3 are the same as those in the first embodiment, the description thereof will be omitted. The member 67 is arranged to face the transfer belt 9 on which the ink image has been formed, with a minute gap therebetween. The ink image on the transfer belt 9 is evenly coated with the petroleum solvent contained in the solvent tank 62 from the solvent supply slit 60 via the supply pump 61. The evenly applied petroleum solvent is recovered from the solvent recovery slit 65 through the recovery pump 66 into the solvent tank 62. Here, the solvent recovery slit 65
Then, since the recovery pump 66 is operated so that a negative pressure is generated at the portion facing the transfer belt 9, not only the petroleum solvent supplied from the solvent supply slit 60 but also the ink image on the transfer belt 9 is detected. The petroleum solvent can be recovered. Here, the colored particles forming the ink image are not peeled off from the surface of the transfer drum 1 because the image force described in the first embodiment is applied between the colored particles and the transfer belt 1. Therefore, it is possible to form an ink image in which the petroleum-based solvent having a uniform thickness is applied on the transfer belt 9 on the colored particles, and the transfer press roller 6 presses the ink image in an appropriate concentrated state. It can be transferred onto the recording paper 8. In this embodiment, the supply pump 61 and the recovery pump 6 are arranged so that the thickness of the petroleum solvent applied to the transfer belt 9 is 5 μm.
6 is activated.

Also in this embodiment, since the evaporation means for evaporating the petroleum solvent forming the ink image is not used, the apparatus is not contaminated by the generation of vapor. Further, since a uniform concentrated ink image can be formed, a good image can be obtained with a low transfer pressure that is not affected by the time from printing to transfer or the print pattern.

[0032]

In the transfer ink jet printer of the present invention, the ink image on the transfer medium is irradiated with ions to fix the colored particles forming the ink on the surface of the transfer medium, and then the ink image is formed. A petroleum-based solvent having a predetermined thickness is transferred onto a recording medium in an appropriate wet state.

Therefore, the ink image can be transferred to the recording medium in a viscous state without using the evaporation means for evaporating the solvent of the ink image on the transfer medium. As a result, there is an effect that the device can be prevented from being contaminated due to the generation of steam. Moreover, since a uniform viscous state of the ink image can be stably realized regardless of the place, the print pattern, or the like,
It has an effect that a high quality transferred image can be stably obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a transfer type inkjet printer according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a transfer type inkjet printer according to a first embodiment of the present invention.

FIG. 3 is a diagram showing an ink image forming operation in the transfer type inkjet printer according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a state at the moment when ink droplets are ejected onto the transfer drum in the first embodiment of the present invention.

FIG. 5 is a diagram showing a state in which the ink image on the transfer drum is concentrated by the ion irradiation means in the first embodiment of the present invention.

FIG. 6 is a perspective view showing a transfer type inkjet printer according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a conventional transfer type inkjet printer.

FIG. 8 is a diagram showing a configuration of a transfer type inkjet printer including a conventional evaporation unit.

[Explanation of symbols]

 1: Transfer drum (transfer medium) 9: Transfer belt (transfer medium) 2: Ink jet recording head 3: Corotron charger (ion irradiation means) 4: Solvent application means 5: Application thickness control means 6: Transfer pressing roller (transfer means) ) 8: Recording paper (recording medium) 20, 42: Petroleum solvent (solvent) 40: Ink image 41: Colored particles 43: Corona ion

Claims (1)

[Claims] 1. An ink in which colored particles are dispersed in a solvent, an ink jet recording head for ejecting the ink as ink droplets, an ink droplet for carrying the ink droplets, and moving through a gap with respect to the ink jet recording head. A transfer medium and a transfer unit that transfers an ink image from the transfer medium to a recording medium. The ink image formed on the transfer medium after the ink image is formed on the transfer medium and before reaching the transfer unit. On the other hand, a transfer type inkjet printer is characterized by sequentially comprising an ion irradiation means for irradiating ions, a solvent application means for applying a solvent, and a solvent thickness regulating means for making the thickness of the solvent constant.